Study on structures and properties of coating film based on silsesquioxanes derived from vinyltrimethoxysilane (VMS)

Vinyl-silsesquioxanes (VS) derived from hydrolytic condensation of vinyltrimethoxysilane (VMS) and modified with tetraethoxysilane (TEOS) (VST) were prepared by sol-gel process. The VS structural characteristics were identified by Fourier transform infrared (FTIR) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOP MS). The ormosil thin films based on VS and VST (m-VS and m-VST) were coated on glass by the dip-coating method. The morphology and thickness of the film were characterized with a scanning probe microscope (SPM) and scanning electron microscope (SEM) device. The film properties of thermodynamics, mechanics and electrochemical corrosion were characterized and studied with differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Nano-Indenter (NI) device and electrochemical impedance spectroscopy (EIS). The results show that the VS was a kind of polyhedral oligomeric silsesquioxanes (POSS) with 1-4 hydroxide, the film with 20% TEOS fraction had the optimum mechanic and corrosion resistance properties, the glass transition temperature was up to 129.8°C, and the weight losses temperature is 337.5°C.